7. Synergistic Effects — The synergistic effects of several toxicants, such as heavy metals, synthetic 
organic compounds and petroleum, can increase an effect to equal more than the sum of the 
insults. This effect may produce results that are much worse than predicted. 
Pathogens 
1. Current Trends — Shellfish beds and swimming areas that are closed should be assessed for 
current trends. Given the present discharge and runoff loading, an assessment should be made 
to foresee any changes in these areas. 
2. Loading — An assessment should be made of the relative contribution of domestic, industrial 
and agricultural discharges to pathogen loading. 
3. Non-Point Sources — The role of urban runoff needs to be compared to other non-point sources. 
4. Accidental Discharges — An assessment of the contribution of accidental or uncontrolled 
(overflow) municipal discharges should be determined. 
Eutrophication 
1. Linear or Nonlinear Effects — The knowledge of effects of a reduction in nutrient loading is not 
well understood. At the present time it is known that reductions in loading decreases nutrient 
concentrations in upper Galveston Bay and other estuaries but it is not known whether the effects 
are linear or nonlinear. The addition may produce a significant lag time due to long mean 
residents times. 
2. In Situ Regeneration — The in situ regeneration of nutrients is highly significant in shallow 
estuaries so the relative importance of this process compared to inputs into the bay ecosystem 
needs to be assessed. 
3. Point and Non-Point Sources — The relative amounts of point and non-point sources of nutrient 
loading need to be determined. Attempts to locate estimated amounts of fertilizer application to 
agricultural lands have been unsuccessful due to lack of adequate records. 
4. Point Source Impacts — The mini-environment around point sources receive larger insults than 
far-field regions. More knowledge about the severe effects near discharge points is needed. 
5. Relationship to Other Processes—Nutrient loading of bay waters may have profound effects on 
natural processes such as denitrification, nitrification, nitrogen fixation and decomposition. The 
interaction of these processes in eutrophic environments is neither well known nor quantified. 
6. Nutrient-Light Interaction — No comprehensive knowledge of nutrient versus light limitation 
of microalgae primary production in Galveston Bay is available. There are large turbidity factors 
from freshwater inflow and wind mixing that can be uncoupled from nutrient inputs. Other 
Texas bays apparently have distinct regions of light-limitation and nutrient limitation. 
7. Relationship of Hypoxia to Discharges — The hypoxic events that occur in the Galveston Bay 
estuary are apparently related to overflows of waste treatment facilities. It is not known whether 
a significant background of organic loading already exists to enhance a minor discharge to cause 
a large impact. 
8. Effects of Hypoxia and Anoxia — The overall effects of hypoxia and anoxia on the biota are not 
known. The possible effects range from minor mortalities to complete losses of year classes or 
spawning populations. The areas of impact may be small but the loss of entire populations or 
organisms may take years to restore. 
Habitat Losses 
1. Future Trends or Losses — The significant losses of Galveston Bay wetlands in the recent past 
have been caused by subsidence from petroleum and water extraction and a mean sea level rise. 
The future losses by these continued processes are not known but a prediction is needed to guide 
effective management strategies. 
2. Creation of Wetlands — As wetlands disappear from Galveston Bay, new wetlands could be 
created by planned spoil disposal and other techniques. The rate of creation of new wetlands that 
matches the decline of submerged wetlands may be difficult to accomplish because of the conflict 
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